The present invention relates generally to motor vehicle control systems and, more particularly, to regulating driver-related electrical adjusting mechanisms in motor vehicles.
Driver-related electrical adjusting mechanisms, for example for motor vehicle seats or motor vehicle steering wheels, are provided in modern motor vehicles to enhance the comfort of the user. Such an electrical adjusting mechanism for a motor vehicle seat is disclosed in DE 195 22 897 C1.
A driver-related electrical adjusting mechanism typically comprises drive elements for the mechanical movement of a motor vehicle component (e.g., a motor vehicle seat or a motor vehicle steering wheel). It also typically comprises operating elements (e.g., switches or multi-functional operating units), which are actuated by the user for the purpose of pre-selecting a desired movement. In addition, an adjusting mechanism usually includes a control unit, in which electrical input signals are converted into actuating signals. One subgroup of the input signals of the control unit may be influenced by the user by actuating the input elements and, therefore, delivers to the control unit information about the actuated inputs. Such input signals are referred to below as operator signals. The drive elements are driven by the actuating signals, which are emitted by the control unit.
The comfort of the user of a motor vehicle is enhanced by a driver-related electrical adjusting mechanism. This enhancement conflicts with the safety risks, which may be generated by hardware defects as well as by improper or inadvertent actuation of the operating elements. For example, in the absence of additional safety measures, a single hardware defect (e.g., decrease or saturation of a voltage level as a consequence of a hardware defect), an erroneous input into a multi-functional operating unit or a jammed switch may result in a motor vehicle seat being moved into a precarious or even unsafe seat position. The seat could, for instance, be moved into a position in which the driver of the motor vehicle can no longer actuate or can actuate only to a limited degree the pedals of the motor vehicle, in particular the brake pedal. Similarly, in the absence of additional safety measures, a motor vehicle component may be moved into a position, in which the function of specific passive safety devices for the protection of the vehicle occupants is not guaranteed. That is, the component may be moved into a position in which these safety devices do not unfold their total effect or they in turn constitute a safety risk (e.g., due to the modified seat position, the minimum distance from the airbag is not achieved).
Current systems do not provide adequate safety measures for the prevention of such safety risks. For example, it is customary to provide in the operating instructions of the motor vehicle or on the operating elements themselves a warning that any actuation of the operating elements while the vehicle is in motion is prohibited. However, such a safety measure that is not implemented in the hardware configuration exhibits the drawback that it can be easily ignored or consciously disregarded by the user of the motor vehicle.
Current systems lack any hardware-implemented safety measures, which preclude the safety-critical movement of a driver-related motor vehicle component, which can be electrically adjusted.
An aspect of the invention is to provide a method for regulating a driver-related electrical adjusting mechanism, by which the operability of the adjusting mechanism is limited in such a way that the movements of the driver-related, adjustable motor vehicle component into a safety-critical position are prevented.
The present invention provides control methods and systems, in which the effect of the operator signals on the actuating signals, leading to the movement of the motor vehicle component, is limited as a function of the operating states of the vehicle. One advantage of the invention lies in the ability to prevent any movement of the motor vehicle component into a safety-critical position by means of such a method both in the case of an improper actuation of the operating elements and in the case of hardware defects in the input elements or the feed lines of the control unit. The present invention also largely preserves for the user the comfort, offered by the driver-related electrical adjusting mechanism, by limiting the movement of the driver-related, adjustable motor vehicle component only to the extent that such a curtailment is necessary from a safety viewpoint.
In one implementation of the present invention, the vehicle speed is regarded as one of the operating states of the motor vehicle. This consideration may be effected, for example, by decreasing monotonically (i.e., under otherwise identical conditions) the effect of the operator signals as the speed of the vehicle increases.
A first embodiment of the invention prevents the motor vehicle component from moving into a safety-critical position by limiting the movement of the motor vehicle component to a defined time interval after the point in time of the last substantial modification of the operator signals. This enables the user to make—for the sake of comfort—a slight adjustment in the position of the motor vehicle component by actuating for a short period of time the operating elements; whereas if an operating element gets stuck or a comparable hardware defect arises, the result is merely a limited movement and, therefore, a non-safety critical movement of the component of the motor vehicle.
Another embodiment of the invention involves limiting the speed of the movement of the motor vehicle component to a defined maximum speed. This prevents the user from being surprised by movements of the motor vehicle component into a safety-critical position as a consequence of an inadvertent or improper actuation of the operating elements or a hardware fault. Thus, in the case of an inadvertent actuation of the operating elements, the user has sufficient reaction time to terminate the adjusting movement or to initiate a movement in the opposite direction. In the case of a hardware defect, this type of curtailment offers the advantage that the user has sufficient time to react to the driving conditions that are changing unintentionally, for example to adjust his seat position on the motor vehicle seat to a changing seat position, and/or to induce a safer stoppage of the vehicle.
A third embodiment of the invention prevents movements of the motor vehicle component into a safety-critical position by limiting the amount of movement of the motor vehicle component to a reduced value range. The reduced value range is less than or equal to the mechanically possible value range for the amount of movement of the motor vehicle component. Thus, there is still the possibility of making a fine adjustment on a small scale for the purpose of the comfort of the user. In contrast, an inadvertent or abnormal adjustment on a larger scale and, thus, perhaps on a safety-critical scale is eliminated.
In the aforementioned embodiments—with a suitable choice of control parameters—the user may bring about a perceptible movement of the driver-related, adjustable motor vehicle component in all positions of the motor vehicle component and in all operating states of the motor vehicle by actuating an operating element, e.g., by depressing a button. Therefore, should the motor vehicle component fail to move, the user is not confused or perhaps diverted from the driving actions.
In yet another embodiment of the present invention, which can be combined with all of the above described embodiments, feedback is provided to the user. The feedback may be in response or a reaction to an actuation of the input elements, the effect of which is limited by the control system, and may signal to the user the presence of the limitation. This feedback may have a visual, auditory or haptic effect on the user. To trigger such feedback, the control unit emits signals that are referred to below as indicating signals. Hence, if the component of the motor vehicle fails to move or, contrary to the user's expectations, moves slightly, the user is not confused or possibly diverted from the driving actions.
Such feedback may also be provided in those positions of the motor vehicle component and in those operating states in which only specific actions of the operator result in a perceptible movement of the motor vehicle component. For example, feedback may be provided at the cutoff points of the mechanically possible value range or at the cutoff points of the value range that is reduced by the automatic control hardware. As an alternative, in the event that the ability to make an adjustment is reduced by the control hardware to the actuation of selected operating elements, the criteria for the regulating procedure may be slightly modified. Such modification may effect a perceptible movement of the motor vehicle component in the event of an arbitrary actuation of an operating element and/or in as many cases as possible of the actuation of an operating element.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.